This invention relates to an X-Y table of general applicability which may be used as a stand-alone unit or which may be used with heating devices such as a heating device for attaching modular electronic components to or removing them from a substrate such as a printed circuit board.
Present day devices for removing or installing modular electronic components from a substrate, such as a printed circuit board include those which use a heated head which contacts each terminal to melt the solder thereon or those which use a blast of hot air to melt the solder. The former devices are generally very complex and employ a heated head having a plurality of spaced apart fingers, each of which must be precisely aligned with each terminal around the component to simultaneously heat the solder thereon. The component is then withdrawn from the substrate by vacuum suction or other mechanical means. The procedure is reversed for installing the component. An example of such a device is disclosed in U.S. Pat. No. 3,382,564. A major disadvantage of this type of device is that due to the ever increasing miniaturization of electronic systems, and individual components therein, the terminals of such components are extremely close together thus making precise alignment of the fingers of the heating head therewith extremely difficult.
Improper alignment or contact often results in solder flowing between terminals on the component thus shorting them or otherwise damaging them. The hot air devices direct a blast of hot air at the terminals from the source above the component to simultaneously melt the solder thereon. Such a device, for example, is disclosed in U.S. Pat. No. 4,366,925. Such a device may function satisfactorily if there is a large spacing between components such that the blast of hot air directed at one component from above will not spill over and melt the solder on the terminals of adjacent components. However, as aforementioned, not only are the components themselves becoming increasingly smaller but their proximity on the printed circuit substrate is also increasing. Thus there is a need for a device which can provide not only a closely controlled and evenly distributed source of heat sufficient to melt solder associated with component terminals or printed substrate conductors during installation or removal of electronic components relative thereto, but one which can rapidly and precisely direct this controlled heat where desired thereby minimizing the likelihood of melting the solder on the terminals of adjacent components or otherwise damaging the printed conductors on the substrate. There is also a need for a device of the aforementioned type which has the capability of precisely positioning the electronic component and its terminals on the ends of the printed conductors on the substrate to ensure no overlapping as well as removing the component to ensure that no liquid solder is smeared on the substrate between the conductors printed thereon.
Such a device is disclosed in the above-mentioned co-pending application Ser. No. 649,065 filed Sept. 10, 1984, now U.S. Pat. No. 4,659,004. In this co-pending application, supporting means for a printed circuit board having one or more components thereon, is clamped to a supporting device which is moveable in the X-Y direction. The supporting device includes a pair of rails having clamps thereon mounted on a box-like frame which is, in turn, mounted on another frame which is moveable in a pair of guides. This device is capable of only very limited movement in the X-Y directions and no table is provided thereon but instead merely a pair of clamps between which a printed circuit board may be clamped. When using this device to remove components from various portions of a printed circuit board of large size, it is necessary to unclamp the board and reclamp the board again with the component aligned as closely as possible with the nozzle which is to deliver the hot air blast to the component terminals and thereby melt the solder thereon. This continual clamping and reclamping of the board is very time consuming.
In co-pending application Ser. No. 762,843, now U.S. Pat. No. 4,682,755, an X-Y positioning system is disclosed which also includes a capability of rotating the work about an axis perpendicular to the X-Y intersection, this rotation being termed .theta. rotation in the present invention. However, this positioning system is also capable of only limited movement in the X-Y directions and no table is provided thereon for support of the printed circuit board; rather, as in the above positioning system, a pair of clamps is provided between which the board may be clamped.